European Journal of Cardiovascular Medicine

Adnexal lesions (ALs) are a prevalent clinical concern among women, significantly contributing to morbidity and mortality. Approximately 5-10% of women undergo surgery for suspected adnexal masses, yet fewer than 25% are ultimately diagnosed as malignant. The management strategy for ALs varies considerably, ranging from simple excision for benign lesions to extensive radical surgery for malignant ones. Therefore, accurate preoperative differentiation between benign and malignant lesions is paramount for guiding appropriate patient care, facilitating proper subspecialty referral, effective surgical planning, and comprehensive patient counselling.[1,2]

Pelvic ultrasound (USG) is typically the initial imaging modality for evaluating suspected ALs due to its widespread availability, cost-effectiveness, and high sensitivity for lesion detection.[3,4] However, USG has limitations, notably its lower specificity for identifying benign lesions (60-95%), its inability to definitively diagnose up to 20% of masses which remain indeterminate, and a restricted field of view often obscured by bowel gas.[4,5]

Magnetic resonance imaging (MRI) offers a superior alternative for evaluating pelvic lesions, largely owing to its excellent soft tissue contrast. T2-weighted MRI images are particularly effective for characterizing soft tissue abnormalities,[6] while T1-weighted and fat-saturated sequences aid in identifying fat-containing lesions (e.g., dermoids) and differentiating them from hemorrhagic lesions. MRI enhances the visualization of both normal pelvic anatomy and pathological findings, demonstrating high sensitivity and specificity in distinguishing benign from malignant pelvic lesions.[2,7]

Correlating findings between USG and MRI in ALs is valuable but can be challenging due to their differing imaging principles, which may lead to discrepancies and impact clinical decisions. Overlapping features or lesion changes can result in false positives or negatives. Both modalities may have limitations in lesion localization, and factors such as operator dependency and variability in interpretation can affect accuracy. This study was undertaken to characterize ALs using USG and correlate the findings with MRI for improved diagnostic clarity.

This prospective cohort study was conducted at the Department of Radio-diagnosis, F.H. Medical College and Hospital, Etmadpur, Agra, over 18 months. The study included 96 patients with clinically suspected pelvic lesions who were initially diagnosed with adnexal pathology on USG and subsequently underwent MRI. Exclusion criteria included individuals with metallic implants or cardiac pacemakers, claustrophobic subjects, and patients who did not undergo surgery or were unwilling to participate. Ethical clearance and informed consent were obtained prior to the study.

Imaging protocols:

USG examinations were performed using a Volusion S8 USG machine. Transvaginal ultrasonography (TVUS) utilized a 10 MHz probe, while transabdominal ultrasonography (TAUS) employed a 3.5 to 5 MHz probe. TAUS was performed with a full bladder for optimal visualization, whereas TVUS was conducted with an empty bladder. The USG assessment involved evaluating ovarian size, echotexture, and the condition of bilateral adnexa and fallopian tubes. For identified adnexal masses, details such as number, size, origin (ovarian, uterine, or extra-ovarian), and morphology (solid, cystic, or complex) were recorded. Observations regarding the uterus and cervix, including any lesions, were also documented.

MRI was performed on a G.E. 1.5 Tesla machine. Multiple sequences were used, including T1-weighted imaging (WI), T1 WI fat saturation, T2 WI, T2 WI fat saturation, and STIR sequences, acquired in axial, coronal, and sagittal planes. Contrast-enhanced imaging and specialized sequences, such as diffusion-weighted and gradient imaging, were applied as needed. MRI helped assess lesion signal characteristics on T1 and T2W images, identifying components like adipose tissue, hemorrhage, fluid, and solid areas. In cases of suspected ovarian carcinoma, MRI also evaluated lesion extent, presence of peritoneal deposits, lymphadenopathy, and ascites. Features suggestive of malignancy included thick enhancing walls, enhancement of solid components, thick septations (enhancing or non-enhancing), and the presence of mural nodules.

Statistical analysis:

Data were recorded in Microsoft Excel and analyzed using SPSS version 26 (SPSS Inc., Chicago, IL, USA). Continuous variables were expressed as mean (standard deviation) or range. Dichotomous and continuous variables were represented as frequency/number and mean ± SD, respectively, and analyzed using the Chi-square test and Student’s t-test. All statistical analyses were performed with a 95% confidence interval, with a P-value of <0.05 or 0.001 considered statistically significant.

The mean age of the study participants was 35.37 ± 12.00 years. The most represented age groups were 21–30 years and 31–40 years, each comprising 31 individuals (32.29%). The 41–50 years group accounted for 17 participants (17.71%), while the 51–60 years group included 6 participants (6.25%). Only 8 participants (8.33%) were aged ≤20 years, and a small proportion (3 participants, 3.13%) were aged above 60 years.

Table 1. Distribution of subjects according to content, nodules, and ascites

Table 2. Distribution of lesions according to diagnostic modalities

Table 3. Distribution of type of adnexal lesions

Table 4. Diagnostic indices of USG in the determination of adnexal lesions

Figure 1. Large multilocuted cyst in pelvis with both ovaries not visualized separately

Figure 2. Abdominopelvic cystic mass with T1 hypo and T2 hyperintense signal with T2 hypointense septae

Figure 3. Complex cystic lesions with multiple sepatations and frank solid cystic component with internal vascularity

Figure 4. Multiloculated cystic lesion with T1/T2 hypointense small eccentric mural nodule and irregular outline

Both USG and MRI showed identical results in characterizing lesion content. Cystic content was detected in 76 participants (79.17%) and solid-cystic content in 20 participants (20.83%), with no discrepancy between the two modalities (P=1.000).

In the detection of nodules, USG identified nodules in 17 participants (17.71%), while MRI detected them in 20 participants (20.83%). The absence of nodules was noted in 82.29% of cases with USG and 79.17% with MRI, with no statistically significant difference between the two (P=0.5846). Similarly, ascites was observed in 13 participants (13.54%) using USG and in 15 participants (15.63%) with MRI. The differences between the modalities in identifying ascites were also not statistically significant (P=0.6824) (Table 1).

Peripheral vascularity on USG was noted in 23 participants (23.96%), followed by septal avascularity in 15 participants (15.63%), and central vascularity in 18 participants (18.75%). Vascularity was absent in 40 participants (41.67%).

MRI enhancement was observed in 22 participants (22.92%), while 74 participants (77.08%) showed no enhancement. Additionally, omental deposits were identified in 15 participants (15.63%) and were absent in 81 participants (84.37%).

Lesion Classification by Diagnostic Modalities:

USG classified 73 lesions (76.04%) as benign and 23 lesions (23.96%) as malignant. MRI identified 73 lesions (76.04%) as benign and 23 lesions (23.96%) as malignant. The P-value of 1.000 indicates no significant difference between USG and MRI in the classification of lesions (Table 2).

USG identified 88 cases (91.67%) as ovarian, whereas MRI classified 83 cases (86.45%) as ovarian. MRI detected more non-ovarian lesions (13 vs. 8), suggesting better accuracy in identifying non-ovarian origins. However, this difference was not statistically significant (p=0.0954) (Table 3).

Of the 73 lesions identified as benign by USG, 70 matched MRI findings, while 3 were found malignant by MRI.  All 20 malignant lesions detected by USG were confirmed by MRI. USG demonstrated sensitivity of 86.96% (95% CI: 66.41%–97.22%) and a negative predictive value (NPV) of 95.89% (95% CI: 89.03%–98.53%). The specificity was 95.89% (95% CI: 88.46%–99.14%), the positive predictive value (PPV) was 86.96% (95% CI: 68.52%–95.33%), and the overall diagnostic accuracy was 93.75% (95% CI: 86.89%–97.67%), confirming USG’s high reliability in identifying malignant lesions (Table 4).

Imaging plays a pivotal role in distinguishing between benign and malignant adnexal masses, thereby guiding appropriate treatment. USG is widely accepted as the preferred initial tool due to its accuracy and accessibility, while MRI serves as a crucial complementary modality when USG results are inconclusive. Given that most ALs are benign, precise imaging assessment is vital for effective clinical management. This study evaluated USG's role in classifying ALs and compared its findings with MRI, highlighting the diagnostic strengths, limitations, and complementary nature of both techniques.

The mean age of the study subjects was 35.37 ± 12.00 years, with the majority falling within the 21-40-year age group. This finding aligns with previous studies indicating a higher prevalence of ALs in this age group, underscoring their clinical importance in women of childbearing age.[1,2,7,8-10]

Both USG and MRI demonstrated similar accuracy in identifying adnexal lesion contents, with most lesions being cystic (79.17%) and no significant difference in detecting cystic or solid-cystic types (P=1.000). This consistency is in line with the frequent occurrence of simple ovarian cysts in clinical practice.[1,8] Similarly, both modalities showed comparable detection rates for nodules and ascites, although MRI offers enhanced tissue characterization. The presence of ascites in a small number of cases (13.54% by USG, 15.63% by MRI) often suggests more complex or advanced pathology.

USG effectively detected various vascular patterns—peripheral (23.96%), septal avascular (15.63%), and central vascularity (18.75%)—which are valuable aids in differentiating benign from malignant lesions. MRI revealed enhancement in 22.92% of lesions, a finding frequently associated with malignancy or aggressive benign tumors. MRI's superior soft tissue contrast makes it more effective in evaluating complex adnexal masses. Furthermore, MRI identified omental deposits in 15.63% of cases. The presence of omental deposits is a critical indicator of advanced malignancy, such as ovarian cancer, highlighting MRI’s indispensable role in disease staging and the detection of peritoneal spread.

In this study, USG and MRI exhibited high agreement in classifying adnexal lesions, with USG and MRI identifying 76.04% as benign and 23.96% as malignant (P=1.000). This indicates no statistically significant difference between the two modalities in overall lesion classification. Previous studies corroborate these findings, supporting USG's reliability for initial evaluation. However, MRI demonstrates superior performance in complex cases, particularly in determining lesion origin and distinguishing fibroids, owing to its advanced imaging capabilities.[1,8]  Adusumilli S et al. similarly noted that USG struggled to determine the origin of uterine cases in 17 out of 20 instances, whereas MRI successfully resolved these diagnostic ambiguities due to its higher multiplanar imaging capabilities and distinct signal characteristics, such as hypointense signal intensity on T2-weighted images.[4]

This study confirms USG as a reliable, accurate, and cost-effective first-line tool for evaluating ALs, offering high sensitivity, excellent NPV, and real-time imaging. Nonetheless, its limitations, such as operator dependency and difficulties in assessing complex or deeply located lesions, necessitate the use of MRI in select cases. Supporting evidence from prior research consistently underscores MRI's superior diagnostic performance. Dasar SK et al. reported higher specificity (96.6%) and accuracy (95%) for MRI compared to USG (90% specificity and 82.5% accuracy).[7] Sohaib et al. also found MRI to have significantly higher specificity (83.7%) than USG (39.5%) in detecting malignancy.[2] Ramya T et al. observed MRI's stronger alignment with histopathology, demonstrating a sensitivity of 91.7%, specificity of 100%, and accuracy of 95.8%, whereas USG showed lower sensitivity (58.3%) and accuracy (79.15%).[9] Furthermore, studies by Mugheri FN, Majeed AI, [10] and Kasim A et al. [11] demonstrated that contrast-enhanced MRI consistently outperformed Doppler USG in characterizing adnexal masses, exhibiting higher sensitivity, specificity, PPV, and NPV. Findings by Sultana N et al. [12]and Abbas TR et al. [13] further affirmed MRI’s superior diagnostic accuracy.

These results highlight the complementary roles of USG and MRI: USG as an effective screening modality, and MRI as a valuable adjunct for detailed assessment, particularly in complex or inconclusive cases. Together, these modalities facilitate accurate diagnosis, improved clinical decision-making, and optimal management of adnexal masses. Despite the present study's findings, it has limitations, including the operator dependency of USG, the absence of histopathological confirmation for all cases, and the lack of follow-up data. Additionally, MRI's limited accessibility and the single-center design may affect the generalizability and diagnostic accuracy of the findings.

Both USG and MRI are essential in the evaluation of adnexal lesions. USG serves as a reliable, cost-effective, and accessible first-line imaging tool for initial assessment and triage. MRI complements USG in complex or ambiguous cases, offering superior tissue characterization and better evaluation of features such as omental deposits and disease extent. While USG demonstrates high diagnostic accuracy, especially in detecting malignancy, MRI adds significant value in staging and detailed lesion analysis. Collectively, these modalities provide a comprehensive approach, aiding early detection and improving clinical management and patient outcomes.

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